1 /*
2 This file creating by running f2c
3 linpack. this version dated 08/14/78
4 cleve moler, university of new mexico, argonne national lab.
5
6 Computes the inverse of a matrix given its factors and pivots
7 calculated by PetscLINPACKgefa(). Performed in-place for an n by n
8 dense matrix.
9
10 Used by the sparse factorization routines in
11 src/mat/impls/baij/seq
12
13 */
14
15 #include <petsc/private/kernels/blockinvert.h>
16
PetscLINPACKgedi(MatScalar * a,PetscInt n,PetscInt * ipvt,MatScalar * work)17 PetscErrorCode PetscLINPACKgedi(MatScalar *a, PetscInt n, PetscInt *ipvt, MatScalar *work)
18 {
19 PetscInt i__2, kb, kp1, nm1, i, j, k, l, ll, kn, knp1, jn1;
20 MatScalar *aa, *ax, *ay, tmp;
21 MatScalar t;
22
23 PetscFunctionBegin;
24 --work;
25 --ipvt;
26 a -= n + 1;
27
28 /* compute inverse(u) */
29
30 for (k = 1; k <= n; ++k) {
31 kn = k * n;
32 knp1 = kn + k;
33 a[knp1] = 1.0 / a[knp1];
34 t = -a[knp1];
35 i__2 = k - 1;
36 aa = &a[1 + kn];
37 for (ll = 0; ll < i__2; ll++) aa[ll] *= t;
38 kp1 = k + 1;
39 if (n < kp1) continue;
40 ax = aa;
41 for (j = kp1; j <= n; ++j) {
42 jn1 = j * n;
43 t = a[k + jn1];
44 a[k + jn1] = 0.;
45 ay = &a[1 + jn1];
46 for (ll = 0; ll < k; ll++) ay[ll] += t * ax[ll];
47 }
48 }
49
50 /* form inverse(u)*inverse(l) */
51
52 nm1 = n - 1;
53 if (nm1 < 1) PetscFunctionReturn(PETSC_SUCCESS);
54 for (kb = 1; kb <= nm1; ++kb) {
55 k = n - kb;
56 kn = k * n;
57 kp1 = k + 1;
58 aa = a + kn;
59 for (i = kp1; i <= n; ++i) {
60 work[i] = aa[i];
61 aa[i] = 0.;
62 }
63 for (j = kp1; j <= n; ++j) {
64 t = work[j];
65 ax = &a[j * n + 1];
66 ay = &a[kn + 1];
67 for (ll = 0; ll < n; ll++) ay[ll] += t * ax[ll];
68 }
69 l = ipvt[k];
70 if (l != k) {
71 ax = &a[kn + 1];
72 ay = &a[l * n + 1];
73 for (ll = 0; ll < n; ll++) {
74 tmp = ax[ll];
75 ax[ll] = ay[ll];
76 ay[ll] = tmp;
77 }
78 }
79 }
80 PetscFunctionReturn(PETSC_SUCCESS);
81 }
82